EP0403915B1 - Vinylidene fluoride polymers and vinylidene fluoride/trifluoroethylene copolymers - Google Patents
Vinylidene fluoride polymers and vinylidene fluoride/trifluoroethylene copolymers Download PDFInfo
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- EP0403915B1 EP0403915B1 EP90111013A EP90111013A EP0403915B1 EP 0403915 B1 EP0403915 B1 EP 0403915B1 EP 90111013 A EP90111013 A EP 90111013A EP 90111013 A EP90111013 A EP 90111013A EP 0403915 B1 EP0403915 B1 EP 0403915B1
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- vinylidene fluoride
- monomer
- trifluoroethylene
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D127/00—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Coating compositions based on derivatives of such polymers
- C09D127/02—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Coating compositions based on derivatives of such polymers not modified by chemical after-treatment
- C09D127/12—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Coating compositions based on derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
- C09D127/16—Homopolymers or copolymers of vinylidene fluoride
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F14/00—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen
- C08F14/18—Monomers containing fluorine
- C08F14/22—Vinylidene fluoride
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F2/00—Processes of polymerisation
- C08F2/46—Polymerisation initiated by wave energy or particle radiation
- C08F2/52—Polymerisation initiated by wave energy or particle radiation by electric discharge, e.g. voltolisation
Definitions
- the invention relates to a method for producing layers of vinylidene fluoride polymers and vinylidene fluoride / trifluoroethylene copolymers.
- ferroelectric plastics For applications in microelectronics, for example as integrable single-layer capacitors (with a capacitance density> 10 nF / cm2) for memory modules, or as piezo- or pyroelectric thin-film elements, polymers based on plastics with ferroelectric properties or at least with a dielectric constant> 5 are required in the unpolarized state.
- the only representatives of ferroelectric plastics so far are polymers made from vinylidene fluoride, i.e. Polyvinylidene fluoride (PVDF), and copolymers of vinylidene fluoride and trifluoroethylene (see, for example: "Appl. Phys. Lett.”, Vol. 36 (1980), pages 286 to 288).
- the polymers or copolymers are then processed to cast films, for example from solutions in methyl ethyl ketone, and the cast films are then - to achieve ferroelectric properties - stretched at temperatures above 100 ° C up to four times the original length and frozen in this state by rapid cooling and / or by means of electric fields up to 100 V / ⁇ m polarized.
- ferroelectric plastics have so far only been available as foils with a minimum thickness of approx. 10 ⁇ m. For applications in microelectronics, however, these materials would have to have a much smaller thickness, down to the sub- ⁇ m range.
- the object of the invention is to provide a method which allows the production of layers of vinylidene fluoride polymers and vinylidene fluoride / trifluoroethylene copolymers with a thickness of ⁇ 10 ⁇ m, but at the same time the dielectric constant or the ferroelectric properties correspond to those of the materials known hitherto.
- a monomer in the form of vinylidene fluoride or a mixture of vinylidene fluoride and trifluoroethylene in a concentration of ⁇ 5.10 ⁇ 9 mol / cm3 is subjected to a low-pressure plasma polymerization excited by microwaves, and that the polymer or copolymer is subjected to an electrical Field strength ⁇ 850 V / cm is deposited on a substrate.
- Electrical Field strength is understood to mean the amplitude E o of the effective field strength in the region of the substrate.
- Plasma polymerisation basically offers the possibility of producing polymers in the form of thin layers. It is also known from EP-PS 0 132 684, when producing so-called glow polymer layers on a substrate - from monomeric hydrocarbons and / or fluorocarbons by means of a high-frequency, low-pressure glow discharge - the glow discharge in the microwave range between 0.5 and 1000 GHz to carry out, with the microwave discharge the amplitude of the effective field strength in the region of the substrate is ⁇ 850 V / cm.
- the microwave discharge is at one pressure from 0.1 to 1 mbar, preferably at a pressure of about 0.5 mbar.
- ethylene, propene, butene, butadiene and cyclohexene can be used as hydrocarbon monomers.
- Perfluorinated compounds serve as fluorocarbons, octafluorocyclobutane being preferred.
- Other perfluorinated compounds that can be used are tetrafluoroethylene, perfluoropropene, perfluorobutene and perfluorocyclohexane.
- Plasma polymers of vinylidene fluoride or of vinylidene fluoride and trifluoroethylene with properties corresponding to conventionally produced polymers have hitherto not been known.
- the reason for the fact that the current method of plasma polymerization does not lead to success with these compounds is probably that fluorine and hydrogen atoms are separated from the molecules of the monomers in low-pressure plasmas under the usual conditions and are removed with the gas stream, so that they are beyond layer formation.
- the plasma polymers therefore have a different elemental composition than the monomers, they are highly cross-linked and cannot be polarized ferroelectrically.
- the low concentration of the monomer is advantageously set in such a way that either the partial pressure of the monomer is ⁇ 100 ⁇ bar or the monomer is used in a mixture with an inert gas at a total pressure> 100 ⁇ bar, the monomer concentration preferably being ⁇ 10% by volume is. Nitrogen or an inert gas is preferably used as the inert gas.
- non-noble gas denotes the gaseous elements helium, neon, argon, krypton and xenon. These substances can be used alone or in a mixture with one another, also in a mixture with nitrogen; argon is preferably used.
- the monomer is thus greatly diluted, ie mixed with an inert gas, or introduced into a low-pressure plasma excited by microwaves with very low density, ie at low pressures; the deposition then takes place at electric field strengths ⁇ 850 V / cm, ie directly at the limit of the visible plasma or just outside this limit.
- an inert gas is used, it can be fed to the plasma polymerization reactor together with the monomer.
- the inert gas is advantageously introduced into the reactor separately from the monomer, directly in the region of the plasma.
- the mixture of vinylidene fluoride and trifluoroethylene preferably contains between 20 and 50 mol% of trifluoroethylene.
- Such mixtures contain vinylidene fluoride and trifluoroethylene, for example in the following ratio (in mol%): 78:22, 73:27, 65:35 and 52:48.
- a so-called plasma polymerization reactor is used to carry out the method according to the invention, in which one or more substrates, for example made of glass or metal or in the form of silicon wafers, are arranged.
- the cylindrical reactor In its central region, the cylindrical reactor is surrounded by a resonator cavity which is connected to a microwave generator (frequency: for example 2.45 GHz).
- the layer is deposited at the border or closely adjacent outside the visible plasma, which is essentially formed in the region of the resonator cavity.
- the layers are generally deposited upstream of the gas, based on the monomer gas.
- the gaseous monomers or monomer mixture is always fed to the reactor outside the visible plasma range, generally at one of the two reactor ends.
- the reactor is connected by a gas line to a storage vessel for the monomer.
- an inert gas such as argon
- a second line can open into this gas line, to which a storage vessel for the inert gas is connected.
- a needle valve, a pressure and a flow meter are arranged in each of the two gas lines.
- the second end of the reactor is through a gas line in which a throttle valve and optionally a cold trap is arranged, connected to a vacuum pump.
- the inert gas is introduced into the reactor separately from the monomer, which is preferably carried out in the region of the centrally arranged resonator cavity, it is advantageous to feed the monomer at both ends of the reactor in order to achieve symmetrical flow conditions; in this case, the mixture of unused monomer and inert gas is removed in the middle of the reactor in the region of the visible plasma.
- the inert gas is supplied in the center, the visible plasma is largely carried by species from the inert gas, and accordingly the monomer is largely kept away from the plasma.
- this method variant - to increase the deposition rate - can introduce a higher amount of monomer gas than is otherwise the case.
- polyvinylidene fluoride is produced from pure, i.e. undiluted vinylidene fluoride or from a mixture of vinylidene fluoride and argon with a proportion of the monomer of 1% by volume.
- a pressure of ⁇ 70 ⁇ bar is set, corresponding to a monomer concentration of approx. 3.10 ⁇ 9 mol / cm3.
- the pressure is approx. 250 ⁇ bar and the monomer concentration is approx. 1.10 ⁇ 10 mol / cm3.
- the power fed into the reactor is 27 W in the first case and 40 W in the second case, corresponding to 14 or 20% of the power of the microwave generator.
- the polymer is deposited upstream of the gas directly outside the visible plasma at field strengths ⁇ 850 V / cm, with layers of 0.3 ⁇ m each being produced.
- the dielectric constant of the polymer layers is above 6 in both cases, the dielectric loss factor at 1 kHz is 5.10 ⁇ 2.
Abstract
Description
Die Erfindung betrifft ein Verfahren zur Herstellung von Schichten aus Vinylidenfluorid-Polymeren und Vinylidenfluorid/Trifluorethylen-Copolymeren.The invention relates to a method for producing layers of vinylidene fluoride polymers and vinylidene fluoride / trifluoroethylene copolymers.
Für Anwendungen in der Mikroelektronik, beispielsweise als integrierbare Einzelschichtkondensatoren (mit einer Kapazitätsdichte > 10 nF /cm²) für Speicherbausteine, oder als piezo- oder pyroelektrische Dünnschichtelemente werden Polymere auf Kunststoffbasis mit ferroelektrischen Eigenschaften oder zumindest mit einer Dielektrizitätszahl > 5 im unpolarisierten Zustand benötigt. Die einzigen Vertreter ferroelektrischer Kunststoffe sind bislang Polymere aus Vinylidenfluorid, d.h. Polyvinylidenfluorid (PVDF), und Copolymere aus Vinylidenfluorid und Trifluorethylen (siehe dazu beispielsweise: "Appl. Phys. Lett.", Vol. 36 (1980), Seiten 286 bis 288).For applications in microelectronics, for example as integrable single-layer capacitors (with a capacitance density> 10 nF / cm²) for memory modules, or as piezo- or pyroelectric thin-film elements, polymers based on plastics with ferroelectric properties or at least with a dielectric constant> 5 are required in the unpolarized state. The only representatives of ferroelectric plastics so far are polymers made from vinylidene fluoride, i.e. Polyvinylidene fluoride (PVDF), and copolymers of vinylidene fluoride and trifluoroethylene (see, for example: "Appl. Phys. Lett.", Vol. 36 (1980), pages 286 to 288).
Die Synthese von Polyvinylidenfluorid, d.h. Poly(1.1-difluorethylenen), und Vinylidenfluorid/Trifluorethylen-Copolymeren erfolgt bisher ausschließlich auf konventionell chemischem Weg, d.h. durch Polymerisation der entsprechenden Monomeren mit Hilfe von Katalysatoren, beispielsweise durch peroxidkatalysierte Emulsions- oder Suspensionspolymerisation von Vinylidenfluorid bei erhöhter Temperatur und erhöhtem Druck. Die Polymeren bzw. Copolymeren werden dann zu Gießfolien verarbeitet, beispielsweise aus Lösungen in Methylethylketon, und die Gießfolien werden dann - zur Erzielung ferroelektrischer Eigenschaften - bei Temperaturen oberhalb 100°C bis zum Vierfachen der ursprünglichen Länge gereckt und in diesem Zustand durch rasche Abkühlung eingefroren und/oder mittels elektrischer Felder bis 100 V/µm polarisiert.The synthesis of polyvinylidene fluoride, ie poly (1,1-difluoroethylene), and vinylidene fluoride / trifluoroethylene copolymers has hitherto been carried out exclusively by a conventional chemical route, ie by polymerizing the corresponding monomers with the aid of catalysts, for example by peroxide-catalyzed emulsion or suspension polymerization of vinylidene fluoride at elevated temperature and increased pressure. The polymers or copolymers are then processed to cast films, for example from solutions in methyl ethyl ketone, and the cast films are then - to achieve ferroelectric properties - stretched at temperatures above 100 ° C up to four times the original length and frozen in this state by rapid cooling and / or by means of electric fields up to 100 V / µm polarized.
Die bekannten ferroelektrischen Kunststoffe sind bislang nur als Folien mit einer Mindestdicke von ca. 10 µm verfügbar. Für die Anwendungen in der Mikroelektronik müßten diese Materialien aber eine sehr viel geringere Dicke aufweisen, und zwar herunter bis zum sub-µm-Bereich.The known ferroelectric plastics have so far only been available as foils with a minimum thickness of approx. 10 µm. For applications in microelectronics, however, these materials would have to have a much smaller thickness, down to the sub-µm range.
Aufgabe der Erfindung ist es, ein Verfahren anzugeben, das die Herstellung von Schichten aus Vinylidenfluorid-Polymeren und Vinylidenfluorid/Trifluorethylen-Copolymeren mit einer Dicke < 10 µm erlaubt, wobei aber gleichzeitig die Dielektrizitätszahl bzw. die ferroelektrischen Eigenschaften denjenigen der bislang bekannten Materialien entsprechen.The object of the invention is to provide a method which allows the production of layers of vinylidene fluoride polymers and vinylidene fluoride / trifluoroethylene copolymers with a thickness of <10 μm, but at the same time the dielectric constant or the ferroelectric properties correspond to those of the materials known hitherto.
Dies wird erfindungsgemäß dadurch erreicht, daß ein Monomer in Form von Vinylidenfluorid oder einem Gemisch aus Vinylidenfluorid und Trifluorethylen in einer Konzentration ≦ 5.10⁻⁹ mol/cm³ einer durch Mikrowellen angeregten Niederdruck-Plasmapolymerisation unterworfen wird, und daß das Polymere bzw. Copolymere bei einer elektrischen Feldstärke < 850 V/cm auf einem Substrat abgeschieden wird. Unter "elektrischer Feldstärke" wird dabei die Amplitude Eo der wirksamen Feldstärke im Bereich des Substrats verstanden.This is achieved according to the invention in that a monomer in the form of vinylidene fluoride or a mixture of vinylidene fluoride and trifluoroethylene in a concentration of ≦ 5.10⁻⁹ mol / cm³ is subjected to a low-pressure plasma polymerization excited by microwaves, and that the polymer or copolymer is subjected to an electrical Field strength <850 V / cm is deposited on a substrate. "Electrical field strength" is understood to mean the amplitude E o of the effective field strength in the region of the substrate.
Die Plasmapolymerisation bietet grundsätzlich die Möglichkeit zur Herstellung von Polymeren in Form dünner Schichten. Aus der EP-PS 0 132 684 ist es außerdem bekannt, bei der Erzeugung von sogenannten Glimmpolymerisat-Schichten auf einem Substrat - aus monomeren Kohlenwasserstoffen und/oder Fluorkohlenstoffen mittels einer Hochfrequenz-Niederdruck-Glimmentladung - die Glimmentladung im Mikrowellenbereich zwischen 0,5 und 1000 GHz durchzuführen, wobei bei der Mikrowellenentladung die Amplitude der wirksamen Feldstärke im Bereich des Substrats ≦ 850 V/cm beträgt. Die Mikrowellenentladung wird dabei bei einem Druck von 0,1 bis 1 mbar durchgeführt, vorzugsweise bei einem Druck von ca. 0,5 mbar.Plasma polymerisation basically offers the possibility of producing polymers in the form of thin layers. It is also known from EP-PS 0 132 684, when producing so-called glow polymer layers on a substrate - from monomeric hydrocarbons and / or fluorocarbons by means of a high-frequency, low-pressure glow discharge - the glow discharge in the microwave range between 0.5 and 1000 GHz to carry out, with the microwave discharge the amplitude of the effective field strength in the region of the substrate is ≦ 850 V / cm. The microwave discharge is at one pressure from 0.1 to 1 mbar, preferably at a pressure of about 0.5 mbar.
Bei diesem Verfahren können beispielsweise Ethylen, Propen, Buten, Butadien und Cyclohexen als Kohlenwasserstoff-Monomere eingesetzt werden. Als Fluorkohlenstoffe dienen perfluorierte Verbindungen, wobei Octafluorcyclobutan bevorzugt wird. Weitere einsetzbare perfluorierte Verbindungen sind Tetrafluorethylen, Perfluorpropen, Perfluorbuten und Perfluorcyclohexan.In this process, for example, ethylene, propene, butene, butadiene and cyclohexene can be used as hydrocarbon monomers. Perfluorinated compounds serve as fluorocarbons, octafluorocyclobutane being preferred. Other perfluorinated compounds that can be used are tetrafluoroethylene, perfluoropropene, perfluorobutene and perfluorocyclohexane.
Plasmapolymerisate aus Vinylidenfluorid bzw. aus Vinylidenfluorid und Trifluorethylen mit Eigenschaften entsprechend konventionell hergestellten Polymerisaten sind bislang nicht bekannt. Der Grund für die Tatsache, daß das gängige Verfahren der Plasmapolymerisation bei diesen Verbindungen nicht zum Erfolg führt, dürfte darin liegen, daß in Niederdruckplasmen unter den üblichen Bedingungen aus den Molekülen der Monomeren Fluor- und Wasserstoffatome abgetrennt und mit dem Gasstrom abgeführt werden, so daß sie der Schichtbildung entzogen sind. Die Plasmapolymerisate weisen somit eine andere Elementarzusammensetzung auf als die Monomeren, sie sind stark vernetzt und ferroelektrisch nicht polarisierbar.Plasma polymers of vinylidene fluoride or of vinylidene fluoride and trifluoroethylene with properties corresponding to conventionally produced polymers have hitherto not been known. The reason for the fact that the current method of plasma polymerization does not lead to success with these compounds is probably that fluorine and hydrogen atoms are separated from the molecules of the monomers in low-pressure plasmas under the usual conditions and are removed with the gas stream, so that they are beyond layer formation. The plasma polymers therefore have a different elemental composition than the monomers, they are highly cross-linked and cannot be polarized ferroelectrically.
Bei der Plasmapolymerisation von Fluorkohlenstoffen, wie Octafluorcyclobutan, d.h. perfluorierten Kohlenwasserstoffen, kann eine strukturschädliche Fluorabspaltung aus den Monomeren zwar nicht in den meist üblichen Radiofrequenz-angeregten Plasmen unterdrückt werden, wohl aber in Mikrowellen-angeregten Plasmen bei der Abscheidung im Bereich niedriger elektrischer Feldstärken, entsprechend dem aus der EP-PS 0 132 684 bekannten Verfahren. Zur Plasmapolymerisation von Verbindungen wie Vinylidenfluorid und Trifluorethylen, die - im Gegensatz zu perfluorierten Kohlenwasserstoffen - (lediglich) partiell fluorierte Kohlenwasserstoffe darstellen, ist aber auch dieses Verfahren nicht geeignet. Offensichtlich führt hierbei nämlich in den Bereichen des Plasmas mit höherer Energiedichte die unvermeidbare Fluor- und Wasserstoffabspaltung aus den Monomeren - aufgrund vergleichsweise hoher Abscheideraten an der Reaktorwand, insbesondere im Bereich des Mikrowelleneintrittspfades - zu leitenden kohlenstoffhaltigen Schichten, welche die Entladung sehr schnell zum Erlöschen bringen.In the plasma polymerization of fluorocarbons, such as octafluorocyclobutane, that is to say perfluorinated hydrocarbons, structurally harmful cleavage of fluorine from the monomers cannot be suppressed in the usually customary radio-frequency-excited plasmas, but in microwave-excited plasmas during the deposition in the range of low electric field strengths the method known from EP-PS 0 132 684. However, this method is also not suitable for the plasma polymerization of compounds such as vinylidene fluoride and trifluoroethylene, which - in contrast to perfluorinated hydrocarbons - are (only) partially fluorinated hydrocarbons. Obviously this leads in the areas of the plasma with higher energy density, the inevitable elimination of fluorine and hydrogen from the monomers - due to comparatively high deposition rates on the reactor wall, especially in the area of the microwave entry path - to conductive carbon-containing layers, which very quickly extinguish the discharge.
Es konnte deshalb nicht vorhergesehen werden und es war sehr überraschend, daß dann, wenn eine vergleichsweise niedrige Konzentration des Monomeren im Plasma eingestellt wird, wie dies beim Verfahren nach der Erfindung der Fall ist, auch Vinylidenfluorid und Trifluorethylen der Plasmapolymerisation zugänglich sind. Die niedrige Konzentration des Monomeren wird dabei vorteilhaft in der Weise eingestellt, daß entweder der Partialdruck des Monomeren < 100 µbar beträgt oder das Monomere im Gemisch mit einem Inertgas bei einem Gesamtdruck > 100 µbar eingesetzt wird, wobei die Monomerkonzentration vorzugsweise < 10 Vol.-% beträgt. Als Inertgas dient dabei vorzugsweise Stickstoff oder ein Edelgas. Mit "Edelgas" werden im Rahmen der vorliegenden Patentanmeldung die gasförmigen Elemente Helium, Neon, Argon, Krypton und Xenon bezeichnet. Diese Stoffe können allein oder im Gemisch untereinander zum Einsatz gelangen, auch im Gemisch mit Stickstoff; bevorzugt wird Argon verwendet.It could therefore not be foreseen and it was very surprising that when a comparatively low concentration of the monomer in the plasma is set, as is the case with the process according to the invention, vinylidene fluoride and trifluoroethylene are also amenable to plasma polymerization. The low concentration of the monomer is advantageously set in such a way that either the partial pressure of the monomer is <100 µbar or the monomer is used in a mixture with an inert gas at a total pressure> 100 µbar, the monomer concentration preferably being <10% by volume is. Nitrogen or an inert gas is preferably used as the inert gas. In the context of the present patent application, “noble gas” denotes the gaseous elements helium, neon, argon, krypton and xenon. These substances can be used alone or in a mixture with one another, also in a mixture with nitrogen; argon is preferably used.
Beim erfindungsgemäßen Verfahren wird das Monomere somit stark verdünnt, d.h. mit einem Inertgas vermischt, oder mit sehr niedriger Dichte, d.h. bei geringen Drücken, in ein mit Mikrowellen angeregtes Niederdruckplasma eingeleitet; die Abscheidung erfolgt dann bei elektrischen Feldstärken < 850 V/cm, d.h. direkt an der Grenze des sichtbaren Plasmas oder dicht außerhalb dieser Grenze. Bei der Verwendung eines Inertgases kann dieses dem Plasmapolymerisationsreaktor zusammen mit dem Monomeren zugeführt werden. Vorteilhaft wird das Inertgas aber getrennt vom Monomeren in den Reaktor eingeleitet, und zwar unmittelbar im Bereich des Plasmas.In the process according to the invention, the monomer is thus greatly diluted, ie mixed with an inert gas, or introduced into a low-pressure plasma excited by microwaves with very low density, ie at low pressures; the deposition then takes place at electric field strengths <850 V / cm, ie directly at the limit of the visible plasma or just outside this limit. If an inert gas is used, it can be fed to the plasma polymerization reactor together with the monomer. However, the inert gas is advantageously introduced into the reactor separately from the monomer, directly in the region of the plasma.
Als Monomeres dient beim erfindungsgemäßen Verfahren Vinylidenfluorid (CH₂=CF₂), d.h. 1.1-Difluorethylen, oder ein Gemisch aus Vinylidenfluorid und Trifluorethylen (CHF=CF₂). Das Gemisch aus Vinylidenfluorid und Trifluorethylen enthält dabei vorzugsweise zwischen 20 und 50 Mol-% an Trifluorethylen. Derartige Gemische enthalten Vinylidenfluorid und Trifluorethylen beispielsweise im folgenden Verhältnis (in Mol-%): 78:22, 73:27, 65:35 und 52:48.The monomer used in the process according to the invention is vinylidene fluoride (CH₂ = CF₂), i.e. 1.1-difluoroethylene, or a mixture of vinylidene fluoride and trifluoroethylene (CHF = CF₂). The mixture of vinylidene fluoride and trifluoroethylene preferably contains between 20 and 50 mol% of trifluoroethylene. Such mixtures contain vinylidene fluoride and trifluoroethylene, for example in the following ratio (in mol%): 78:22, 73:27, 65:35 and 52:48.
Anhand von Ausführungsbeispielen soll die Erfindung noch näher erläutert werden.The invention will be explained in more detail with the aid of exemplary embodiments.
Zur Durchführung des erfindungsgemäßen Verfahrens dient ein sogenannter Plasmapolymerisationsreaktor, in welchem ein oder mehrere Substrate, beispielsweise aus Glas oder Metall oder in Form von Siliciumwafern, angeordnet sind. Der zylinderförmige Reaktor ist in seinem zentralen Bereich von einer Resonatorkavität umgeben, die an einen Mikrowellengenerator (Frequenz: beispielsweise 2,45 GHz) angeschlossen ist. Die Abscheidung der Schicht vollzieht sich jeweils an der Grenze bzw. dicht benachbart außerhalb des sichtbaren Plasmas, das sich im wesentlichen im Bereich der Resonatorkavität ausbildet. Dabei erfolgt die Schichtabscheidung im allgemeinen gasstromaufwärts, bezogen auf das Monomergas.A so-called plasma polymerization reactor is used to carry out the method according to the invention, in which one or more substrates, for example made of glass or metal or in the form of silicon wafers, are arranged. In its central region, the cylindrical reactor is surrounded by a resonator cavity which is connected to a microwave generator (frequency: for example 2.45 GHz). The layer is deposited at the border or closely adjacent outside the visible plasma, which is essentially formed in the region of the resonator cavity. The layers are generally deposited upstream of the gas, based on the monomer gas.
Das gasförmige Monomere bzw. Monomerengemisch wird dem Reaktor stets außerhalb des sichtbaren Plasmabereiches zugeführt, im allgemeinen an einem der beiden Reaktorenden. Der Reaktor ist dazu durch eine Gasleitung mit einem Vorratsgefäß für das Monomere verbunden. Bei der Verwendung eines Inertgases, wie Argon, kann in diese Gasleitung eine zweite Leitung münden, an die ein Vorratsgefäß für das Inertgas angeschlossen ist. In den beiden Gasleitungen sind jeweils ein Nadelventil, ein Druck- und ein Durchflußmeßgerät angeordnet. Das zweite Ende des Reaktors ist durch eine Gasleitung, in der ein Drosselventil und gegebenenfalls eine Kühlfalle angeordnet ist, mit einer Vakuumpumpe verbunden.The gaseous monomers or monomer mixture is always fed to the reactor outside the visible plasma range, generally at one of the two reactor ends. For this purpose, the reactor is connected by a gas line to a storage vessel for the monomer. When using an inert gas, such as argon, a second line can open into this gas line, to which a storage vessel for the inert gas is connected. A needle valve, a pressure and a flow meter are arranged in each of the two gas lines. The second end of the reactor is through a gas line in which a throttle valve and optionally a cold trap is arranged, connected to a vacuum pump.
Wird das Inertgas getrennt vom Monomeren in den Reaktor eingeleitet, was vorzugsweise im Bereich der mittig angeordneten Resonatorkavität erfolgt, so ist es vorteilhaft, das Monomere - zur Erzielung symmetrischer Strömungsverhältnisse - an beiden Reaktorenden zuzuführen; die Abführung des Gemisches aus unverbrauchtem Monomeren und Inertgas erfolgt in diesem Fall dann in der Mitte des Reaktors im Bereich des sichtbaren Plasmas. Bei mittiger Zuführung des Inertgases wird das sichtbare Plasma weitestgehend von Spezies aus dem Inertgas getragen, und dementsprechend wird das Monomere weitgehend vom Plasma ferngehalten. Da auf diese Weise ein viel geringerer Anteil von Monomermolekülen durch das Plasma strukturschädigend angeregt wird als dies bei der Abwesenheit von Inertgas der Fall ist, kann bei dieser Verfahrensvariante - zur Erhöhung der Abscheiderate - ein höherer Monomergaseintrag erfolgen als dies sonst der Fall ist.If the inert gas is introduced into the reactor separately from the monomer, which is preferably carried out in the region of the centrally arranged resonator cavity, it is advantageous to feed the monomer at both ends of the reactor in order to achieve symmetrical flow conditions; in this case, the mixture of unused monomer and inert gas is removed in the middle of the reactor in the region of the visible plasma. When the inert gas is supplied in the center, the visible plasma is largely carried by species from the inert gas, and accordingly the monomer is largely kept away from the plasma. Since in this way a much smaller proportion of monomer molecules are excited by the plasma to damage the structure than is the case in the absence of inert gas, this method variant - to increase the deposition rate - can introduce a higher amount of monomer gas than is otherwise the case.
Die Herstellung von Polyvinylidenfluorid erfolgt beispielsweise aus reinem, d.h. unverdünntem Vinylidenfluorid oder aus einem Gemisch von Vinylidenfluorid und Argon mit einem Anteil des Monomeren von 1 Vol.-%. Im ersten Fall wird ein Druck < 70 µbar eingestellt, entsprechend einer Monomerkonzentration von ca. 3.10⁻⁹ mol/cm³. Im zweiten Fall beträgt der Druck ca. 250 µbar und die Monomerkonzentration ca. 1.10⁻¹⁰ mol/cm³. Die in den Reaktor eingespeiste Leistung beträgt im ersten Fall 27 W und im zweiten Fall 40 W, entsprechend 14 bzw. 20 % der Leistung des Mikrowellengenerators.For example, polyvinylidene fluoride is produced from pure, i.e. undiluted vinylidene fluoride or from a mixture of vinylidene fluoride and argon with a proportion of the monomer of 1% by volume. In the first case, a pressure of <70 µbar is set, corresponding to a monomer concentration of approx. 3.10⁻⁹ mol / cm³. In the second case the pressure is approx. 250 µbar and the monomer concentration is approx. 1.10⁻¹⁰ mol / cm³. The power fed into the reactor is 27 W in the first case and 40 W in the second case, corresponding to 14 or 20% of the power of the microwave generator.
In beiden Fällen erfolgt die Abscheidung des Polymeren gasstromaufwärts unmittelbar außerhalb des sichtbaren Plasmas bei Feldstärken < 850 V/cm, wobei jeweils 0,3 µm dicke Schichten hergestellt werden. Die Dielektrizitätszahl der Polymerschichten liegt in beiden Fällen über 6, der dielektrische Verlustfaktor bei 1 kHz beträgt 5.10⁻².In both cases, the polymer is deposited upstream of the gas directly outside the visible plasma at field strengths <850 V / cm, with layers of 0.3 µm each being produced. The dielectric constant of the polymer layers is above 6 in both cases, the dielectric loss factor at 1 kHz is 5.10⁻².
Claims (7)
- Process for preparing layers of vinylidene fluoride polymers and vinylidene fluoride trifluoroethylene copolymers, characterised in that a monomer in the form of vinylidene fluoride or a mixture of vinylidene fluoride and trifluoroethylene in a concentration of ≦ 5x10⁻⁹ mol/cm³ is subjected to a low pressure plasma polymerisation which is excited by microwaves, and in that the polymer or copolymer is deposited onto a substrate at an electric field strength of <850 V/cm.
- Process according to claim 1, characterised in that the mixture of vinylidene fluoride and trifluoroethylene contains between 20 and 50 mol% trifluoroethylene.
- Process according to claim 1 or 2, characterised in that the partial pressure of the monomer amounts to < 100 µbar.
- Process according to claim 1 or 2, characterised in that the monomer is used in the mixture with an inert gas at a total pressure of > 100 µbar.
- Process according to claim 4, characterised in that the monomer concentration in the mixture amounts to < 10 vol %.
- Process according to claim 4 or 5, characterised in that nitrogen or a noble gas, in particular argon, is used as the inert gas.
- Process according to one of claims 4 to 6, characterised in that the inert gas is introduced separately from the monomer into the plasma polymerisation reactor, directly within the region of the plasma.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AT90111013T ATE89292T1 (en) | 1989-06-22 | 1990-06-11 | VINYLIDENE FLUORIDE POLYMERS AND VINYLIDENE FLUORIDE/TRIFLUORO ETHYLENE COPOLYMERS. |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3920535 | 1989-06-22 | ||
| DE3920535 | 1989-06-22 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0403915A1 EP0403915A1 (en) | 1990-12-27 |
| EP0403915B1 true EP0403915B1 (en) | 1993-05-12 |
Family
ID=6383382
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP90111013A Expired - Lifetime EP0403915B1 (en) | 1989-06-22 | 1990-06-11 | Vinylidene fluoride polymers and vinylidene fluoride/trifluoroethylene copolymers |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US5035917A (en) |
| EP (1) | EP0403915B1 (en) |
| JP (1) | JPH0344468A (en) |
| AT (1) | ATE89292T1 (en) |
| DE (1) | DE59001410D1 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4207422C2 (en) * | 1992-03-09 | 1994-11-24 | Fraunhofer Ges Forschung | Process for the production of thin, microporous, conductive polymer layers |
| US5635812A (en) * | 1994-09-29 | 1997-06-03 | Motorola, Inc. | Thermal sensing polymeric capacitor |
| DE19547934A1 (en) * | 1995-12-22 | 1997-06-26 | Deutsche Telekom Ag | Process for the preparation of a pyroelectric mixture |
| JP3897853B2 (en) * | 1997-03-12 | 2007-03-28 | 株式会社アルバック | Method for producing water-repellent window material |
| GB9712338D0 (en) | 1997-06-14 | 1997-08-13 | Secr Defence | Surface coatings |
| ES2252840T3 (en) | 1997-06-14 | 2006-05-16 | The Secretary Of State For Defence | SURFACE COATINGS. |
| GB0406049D0 (en) | 2004-03-18 | 2004-04-21 | Secr Defence | Surface coatings |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4382985A (en) * | 1980-10-11 | 1983-05-10 | Daikin Kogyo Co., Ltd. | Process for forming film of fluoroalkyl acrylate polymer on substrate and process for preparing patterned resist from the film |
| DE3326377A1 (en) * | 1983-07-22 | 1985-01-31 | Siemens AG, 1000 Berlin und 8000 München | METHOD FOR PRODUCING GLIMP POLYMERISATE LAYERS |
-
1990
- 1990-05-25 US US07/529,246 patent/US5035917A/en not_active Expired - Fee Related
- 1990-06-11 AT AT90111013T patent/ATE89292T1/en not_active IP Right Cessation
- 1990-06-11 DE DE9090111013T patent/DE59001410D1/en not_active Expired - Fee Related
- 1990-06-11 EP EP90111013A patent/EP0403915B1/en not_active Expired - Lifetime
- 1990-06-15 JP JP2155565A patent/JPH0344468A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| DE59001410D1 (en) | 1993-06-17 |
| JPH0344468A (en) | 1991-02-26 |
| US5035917A (en) | 1991-07-30 |
| EP0403915A1 (en) | 1990-12-27 |
| ATE89292T1 (en) | 1993-05-15 |
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